281 

 48. Ptychogaster investigator is, Alcoek & Anderson. 



Ptychogaster investigatoris, Alcoek and Anderson, Ann. Mag. Nat. Hist., Jan. 1899, p. 2+. 



TlLUSTBATIONS OF THE ZOOLOGY OF THE INVESTIGATOR, CRUSTACEA, PLATE XLV. FlG. 1. 



Carapace short, its length (including the rostrum, which is between a half 

 and a third that of the rest of the carapace) is only equal to that of the first 

 five and a half fully extended abdominal terga ; its surface is everywhere studded 

 with spinules and spines, the largest of which show a tolerably plain arrange- 

 ment in four longitudinal series. 



The only abdominal tergum (besides the telson) that is perfectly free from 

 spines is the third : the first tergum has a transverse spiny carina continuous 

 with a similar carina on the edge of either pleura of the second segment ; the 

 second has a transverse raised row of four large spines, besides several teeth ; 

 both the fourth and fifth are separated from their pleura on either side by a 

 longitudinal row of two or three spines or serrations but are otherwise smooth ; 

 the sixth is covered with retrorse spinules and spines, including three conspicuous 

 transverse series, of which the last far overhang the telson. 



The first segment of the telson is hardly perceptibly shorter, and slightly 

 narrower, than the second ; the surface of both bears some inconspicuous capillary 

 spinelets or bristles. 



The pleura of the third and fourth abdominal somites are devoid of spines. 



The external maxillipeds are unarmed, except for the ischial serrations, and 

 aic very hairy in their distal half. 



Chelipeds and legs long, slender, and spiny ; the chelipeds in the female 

 (male unknown) are about 2- times the length of the fully extended body and 

 half as long again as the legs ; the racquet-like form of the hand, due to the 

 bowing of the basal half of the fingers, is more than ordinary conspicuous. 



Of the first three pair of legs the first is slightly the longest and the second 

 slightly the shortest ; the dactyli of all are hardly more than a quarter the length 

 of the propodites. 



A female from the Andaman Sea, 405 fathoms, is 55 millim. in length when 

 fully extended, and has chelipeds 132 millim. and first legs 91 millim. long. 



The eyes are large and rather pale. 



Regd. No. -7jj- (Type of the species). 



Uroi'TVChus, Henderson. 



Dipti/chutt, A. Milne Edwards, Bull. Mus. Comp. Zool., VIII. 1880, p. 61, and Milne Edwards and Bouvier, 

 Ann. Sci. Nat. Zool., (7) XVI. 1894, p. 303, and Mem. Mus. Comp. Zool. XIX. No. 2, 1897, p. 123 (nom. prseoec). 

 Uroptychus, Henderson, Challenger Anoraura, p. 173. 



Carapace somewhat depressed with the lateral borders well defined, broader 

 36 



